The LM1875 is, interestingly, quite different from its newer "Overture series" brethren (which in turn all use the same basic topology). At the very least, the equivalent circuit looks a lot less intimidating, but there also are lots of other differences. Spec wise, the '1875 has a peculiar kink in its THD vs. output power graphs; as a result, distortion in the critical 1 W area is a lot higher.

Taking a look at pricing, the '1875 is a good bit cheaper (at least 1/3) compared to any of its successors, but as mentioned, for good reason. (Or maybe its internals have long since been replaced? It's not looking bad at all when measured here, even though the '3886 still does better at 4 times the gain.)

In which order did these chips appear anyway? There's a bewildering array, with at least the single amps 1876, 3875, 3876, 3886 and 4700 and the duals 1876, 4765, 4766 and 4780. All of them prefer the lighter 8 ohm loads, but for some reason 4766 and 4780 seem particularly bothered by 4 ohms if you look at 20 kHz distortion.

Speaking of the LM1876, this one actually finds use as output driver in at least one line of (well-reputed) commercial headphone amps, tweaked for lower gain.

I currently have a pair of active speakers set up using the 3886 for the midrange, and the 1875 for the tweeters. I have been running this setup for about 2 years. Technical arguments aside, the 3886 is a much more functional amp for my purposes. The 1875 has a terrible thump at power cycling, and has necessitated a relay to protect my drivers. I would not recommend using the 1875 without some additional protection for any sensitive drivers.

Now we're into failure modes of the 1875: if you're super lucky nothing will happen, if you're slightly lucky the chip will just die and output 0 V, if you're lucky the chip will put out a small +2V glitch before it dies and hopefully your speakers survive ...

Now we get into the unlucky : if your unlucky the chip will put out +15 V for a while before it dies (do you like the smell of woofer in the morning?), if you're really unlucky it will oscilate / clip then put out +32 Vdc then die (hope you didn't like those tweeters too much?) and if your really unlucky something unpredictable and even worse will happen!
DON"T run your LM1875 at +/- 29 Vdc!

Now what I didn't tell you is that they're just hooked up to my lab speakers (no big deal), I've tortured them and they've survived and I've monitored my house voltage and it doesn't seem to spike (but it could!). So I'm not as insane as I first appear.

Hopefully that makes sure no one blows a chipamp.

Cheers,
Jeff

(Sorry Andrew, my previous post was a little on the irresponsible side. Remember, they're usually misinformed not deliberately trying to misinform.